Environmental and economic challenges resulting from the application of nitrogen fertilizers have increased concerns about its productivity in the agricultural systems. This study was conducted to evaluate SSM-Wheat model to simulate nitrogen budgeting with various nitrogen application scenarios (Dry land-without nitrogen, Dry land-low nitrogen, Irrigated-without nitrogen, Irrigated-conventional, Irrigated-high nitrogen and Irrigated-very high nitrogen) in rainfed and irrigated conditions in the wheat-based cropping systems of Gorgan region in Iran in a 21-years period (1990-2010). Results indicated that the average total losses of nitrogen were significantly different among different scenarios. In all scenarios, the proportion of nitrogen loss (81%), as gaseous was more than that of leaching (19%). Nitrogen loss by nitrification ranged between 5.9 and 59.2 kg.ha-1 with average 23.2 kg.ha-1 while nitrogen volatilization ranged between 0 and 14.9 kg.ha-1 with an average 5.8 kg.ha-1. Also, the maximum nitrogen leached was associated with irrigated wheat-high nitrogen scenario that had significant difference with other scenarios. However, the lowest amount observed in the rainfed wheat-without nitrogen scenario that had no significant difference with irrigated wheat-without nitrogen scenario. The highest productivity was observed in irrigated wheat-conventional scenarios (26 kg.kg-1) and irrigated wheat high nitrogen (25.9 kg.kg-1) which was significantly different than the other scenarios. Therefore, irrigated wheat- conventional scenario was identified as suitable scenario in wheat production in Gorgan, Iran, due to cost saving, low leaching, less environmental pollution, adequate irrigation and less fertilizer use.